Question

Which peaks in your IR spectrum match the known structure of caffeine? for each diagnostic peak, you should identify its frequency in wavenumbers and the probable vibration (e.q 2950 cm, alkane C-H stretch). You should then write a short discussion that matches the diagnostic peaks to a functional group in caffeine structure

Label all the function groups

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Answer 1

IR Peak analysis 2955 sp3 C-H stretching 1720 non-conjugated amide C=O stretching 1662 conjugated amide C=O stretching 1600 C=C stretching 1487 CH3 rocking 1380 C-H bending 1241 C-N stretching The C=C is tetrasubstituted hence we dont see any sp2 C-H stretching around 3010 and C-H wag around 890. The weak peak around 3110 is of overtone for C=O. 1662 CH3 H3C 10 1702 1600 N CH3